We consider non-stationary dynamical systems with one-and-a-half degrees of freedom. We are interested in algorithmic construction of rich classes of Hamilton's equations with the Hamiltonian H = p 2 /2 + V (x, t) which are Liouville integrable. For this purpose we use the method of hydrodynamic reductions of the corresponding one-dimensional Vlasov kinetic equation.Also we present several examples of such systems with first integrals with nonpolynomial dependency w.r.t. to momentum.The constructed in this paper classes of potential functions V (x, t) which give integrable systems with one-and-a-half degrees of freedom are parameterized by arbitrary number of constants.